Cementitious slab and means and method for forming same with lines of weakness



12, 1954 H. J. PETERS 5 1 CEMENTITIOUS SLAB AND MEANS AND METHOD FOR F NG SAME W LINES 0F WEAKNESS F d May 2. 1960' r g If! 3 I INVENTOR. firlan J Peters United States Patent CEMENTITIOUS SLAB AND MEANS AND METHOD FOR FORMING SAME WITH LINES F WEAKNESS Harlan J. Peters, Whittier-{Calm (9616 EaBeverlyRoad, Pico-Rivera, Calif.), assignor of one-half to Lin W. Bowling, Pica-Rivera, Calif. a

Filed May 2, 1960, Ser. No. 26,268

g 3 Claims. (Cl. 94-22) This invention relates to a slab formedof cementitious material such as concrete floors, particularly such as are constructed in buildings and especially slabs of an area rendering necessary the employment of joints. forming lines of weakness along which the slab may fracture on contraction thereof. r

An object of the invention is to produce a cementitious slab of theabove character with an improved joint or joints dividing or separating surface areas of the slab and producing. defined lines of :weakness therein, wherein the joints are resilient and are accordinglydeformable under expansion and contraction of the slab, and whereby cracks or fissures developed along the joints are rendered inconspicuous and are fortified against marginal chipping. s

. Another object is to provide an improved partition strip for permanent imbedding into a cementitious slab to affordftherein a desired line of weakness and which strip embodies a construction whereby it may be adjusted after beingimbedded to align with the surface. of the slab.

Another object is to provide a means of producing a cementitious slab with defined surface areas thereof separated by imbedded joint-forming partitions, wherein the partitions are soformed and arranged as to permit troweling of the cement surface of the slab and effect finished leveling of the slab across the joint.

A further object is to providethe joint former with a web wherein when the cement has initially set yet subject to surface troweling, the web may be raised or lowered relative to the body of cement, if need be, so that when finished the web will be permanently imbedded inthe concrete with the upper margin thereof flush with the cement surface. a s

. With the foregoing objects in view together with such other objectsand advantages as may subsequently appear, the invention resides in the parts andin theeombination, construction and arrangement of parts hereinafter described. and claimed and as, illustrated by way of example in the accompanying drawings in which: i

length of FIG. 1 is an isometric view of a fragmentary the joint-forming partition showing it as fitted with a 'telescopic sectionfor varying the lengththereof: M

FIG. 2 is a view in cross section taken on the line 2-2 ofFIG.1: i

FIG.'3 is a view in cross section as seen on the line 3--3 of FIG. 1 showing the telescoped'section:

FIG. 4 isfa view in section of a fragmentary portion of a cementitious slab or floor as equippedwiththe jointforming partition shown in FIG. 1: s 7

FIG. 5 is a diagram in section depicting the manner of initially irnbedding the joint-forming partition in the cementitious body: and

FIG. 6 is a view similar to FIG. 5 showing the manner in which an adjustable web embodied in the partition is elevated from the imbedded position shown in FIG. 5 to a position projecting above the surface of the slab and preliminary to depression of the web to align its upper margin with the surface of the slab as shown in FIG. 4.

Referring to the drawings more specifically A indicates generally the joint-forming partition which embodies an standing inwardly converging side walls 89, and the web C comprises an elongated narrow strip of rectangular cross-section which is interposed between the sidewalls 8,-9 and is slidably contacted thereby. on its opposite parallel sides for movement in the directions of itslength and width relative to theychannel strip B. The outer margins of the side walls 89 normally abut each other so as to be spread apart on interposingthe WebC therebetween to thereby afford close sliding contact between such margins and the opposite sides of the web C. The web C is permanently assembled'relative to the channel strip B in telescopic engagement'therewith with its upper margin projecting above the upper margins of the side walls 8-9 of the channel strip B and with its lower margin spaced from the bottom wall 7 as shown in FIG. 2.,

In orderto enable depression of the channel strip B, bottom wall down, intota body of soft cementitious material to completely submerge the strip therein with the upper margins of the side walls 8-9 imbedded beneath the surface of the cementitious body, as later described, such margins are free and the outer surfaces of the'side walls are devoid of obstructions such as would interfere with depressing the strip into thecementitious body.

The channel strip B and Web C are preferably formed. of suitable sheet metal of any desired thickness, and are of any suitable dimensions but preferably have an over-all height from the bottom wall 7 to the upper margin of the by telescoping the contiguous ends of adjacent sections in the ends of a coupling channel section Econtoured to slidably conformto the exterior ofthe channel section B as shown in FIG. 3 and as indicated at the right-hand side of FIG. 1.

In some instances the channel section F may constitute in itself an elongation of a channel strip B. In producing a cementitious slab having lines of weakness, the cementitious material, such as concrete, is formed and applied in a soft plastic state in the usual manner to form the desired body D thereof the surface of which is roughly leveled in any desired, manner.

While the body of cementitious material is soft, lengths of the joint-forming partition A are imbedded in the body D as byimpressing the strips bottom-wise into the plastic mass or by setting the strips and applying the material therearound and over; the partition being thus completely submerged with the upper margin ofthe web C extend-l ing beneath and spaced a short distance from the surface I F of the body D" as shown in FIG. 5. The surface F is then troweled in a usuallmanner tobring it to' the desired finished or seini-finished state, which may readily be ac. complished since the partition A being beneath the surface F will not interfere with the troweling operation.

When the material of the body D has set to the stage when its surface F is in condition for finished troweling, the web C is then elevated relative to the imbedded channel B so that the upper margin of the web will project above the surface F as shown in FIG. 6. This is accomplished by grasping the submerged web C by a suitable tool, such as pliers, which can readily penetrate the material at this stage and be engaged with the web.

The web C is then depressed, as by means of a hand trowel, and positioned with its upper edge flush with the surface F as shown in FIG. 4, during which operation the surface F adjacent the upper margin of the web is worked, as by troweling, to remedy any dislodgement of the cementitious material as may have been occasioned by adjustment of the web, and to bring the surface of the material of the body D and the margin of the web flush with each other.

In order to effect the above recited manipulation of the web C, whi lifipepmgngi tly assembled in the channel y supported thereby, the web C necessarily has a width exceeding the length of its transverse movement relative to the channel B so'that when the web C is in its elevated position relative to the imbedded channel B, as shown in FIG. 6, the lower marginal portion of the web C will project into the void interiorly of the channel whereby the margins of the side walls 8-9 of the channel will overlie the web C in sliding contact with the parallel side faces of the web C. The margins of the side walls 8-9 will thus be maintained in sliding abutting contact with the opposite sides of the web throughout lateral movement of the web relative to the channel B, whereby the margins of the side walls 89 will act on lateral movement of the web C relative thereto to scrape the sides of the web throughout the width thereof and will be maintained in sealing contact with the sides of the web C irrespective of the extent of its marginal projection from the channel, thereby effectively sealing the interior of the channel against the ingress of particles of cement at all times. This sealing action is augmented by the outer margins of the side walls of the channel normally abutting each other and being spread apart by insertion of the web C therebetween.

From the foregoing it will be seen that in carrying out the invention the channel strip B is initially completely imbedded and submerged in the body D of soft cementitious material together with either all or a portion of the upwardly projecting web C protruding from the submerged upper margin of the channel strip, as shown in FIGS. 5 and 6 whereby the finished body D will be monolithic with the joint forming partition A comprising the channel strip B and web C imbedded therein up to the outer edge of the web, as shown in FIG. 4.

While a specific embodiment of the invention has been shown and described it is not limited to the exact structure set forth, but is subject to such modifications as come within the scope of the appended claims.

I claim:

1. The method of forming a building floor or other load-supporting monolithic slab of cementitious material with a line of weakness, said method consisting in initially forming a panel of a mass of wet plastic cementitious material, leveling the upper surface of the mass, pressing an elongated stiff narrow channel-providing member and associated channel-carried flat strip of sheet material edgewise into the mass while the mass is in a soft plastic state and with the channel presented upward to dispose both said channel-providing member and strip beneath and adjacent the upper surface of the mass in spaced and substantially parallel relation to said surface; and then dividing the portion of the mass overlying the imbedded channel and strip throughout the length thereof by elevating the strip of sheet material from along and relatively of 4 said channel through the mass to dispose the upper strip edge at least in plane with the upper surface of the mass while maintaining contact between the channel and the lower portion of the strip of sheet material.

2. The method of forming a building floor or other load-supporting monolithic slab of cementitious material with a line of weakness, consisting in initially forming a panel of a mass of wet plastic cementitious material, leveling the surface of the mass, pressing an elongated stiff narrow channel-providing member and an associated flat channel-carried strip of sheet material edgewise into the mass while the mass is in a soft plastic state, with the channel presented upward, until the upper edges of the channel and strip are disposed beneath and adjacent the upper surface of the mass in spaced and substantially parallel relation to said surface; then dividing the portion of the mass overlying the channel and strip throughout the length thereof by elevating said strip of sheet material from along and relatively of said channel to near the upper surface of said mass while maintaining contact between said strip and channel; troweling the upper surface of the mass above said channel and strip; then while the mass is in a soft plastic state, elevating the strip throughout its length to position its upper edge at least slightly above the upper surface of the mass while maintaining contact between the channel and the lower portion of the strip; then after allowing the mass to nearly set, depressing the strip to bring its upper edge flush with the surface of the mass, and coincidently troweling the upper mass surface to a finished level on a plane with the upper edge of said strip.

3. The method of forming a line of weakness in a monolithic building floor or other load-supporting slab of cementitious material which method comprises initially at least substantially leveling the surface of a slab-form body of freshly poured wet soft plastic cementitious material; then impressing into the slab material while soft 21 joint member embodying an upwardly presented channel having a vertically movable web permanently in service projecting from said channel along the length thereof in slidable telescopic engagement therewith, said joint member being impressed into said soft slab body material to completely submerge said channel together with the lower portion of said web in said slab body material with the upper marginal portion of said web projecting above the leveled upper surface of said slab body; subsequently depressing said web into said channel, while maintaining contact with both sides of the latter, to align its upper web edge with the surface of the slab body and then allowing the cementitious material of the slab to harden with the channel and web permanently imbedded therein to form a line of weakness in said slab along the plane of said joint member.

References Cited in the file of this patent UNITED STATES PATENTS 1,368,374 Turco Feb. 15, 1921 1,544,733 Ferrarini July 7, 1925 1,667,313 Galassi Apr. 24, 1928 2,129,325 Holter Sept. 6, 1938 2,949,828 Carnes Aug. 23, 1960 

3. THE METHOD OF FORMING A LINE OF WEAKNESS IN A MONOLITHIC BUILDING FLOOR OR OTHER LOAD-SUPPORTING SLAB OF CEMENTITIOUS MATERIAL WHICH METHOD COMPRISES INITIALLY AT LEAST SUBSTANTIALLY LEVELING THE SURFACE OF A SLAB-FORM BODY OF FRESHLY POURED WET SOFT PLASTIC CEMENTITIOUS MATERIAL; THEN IMPRESSING INTO THE SLAB MATERIAL WHILE SOFT A JOINT MEMBER EMBODYING AN UPWARDLY PRESENTED CHANNEL HAVING A VERTICALLY MOVABLE WEB PERMANENTLY IN SERVICE PROJECTING FROM SAID CHANNEL ALONG THE LENGTH THEREOF IN SLIDABLE TELESCOPIC ENGAGEMENT THEREWITH, SAID JOINT MEMBER BEING IMPRESSED INTO SAID SOFT SLAB BODY MATERIAL TO COMPLETELY SUBMERGE SAID CHANNEL TOGETHER WITH THE LOWER PORTION OF SAID WEB IN SAID SLAB BODY MATERIAL WITH THE UPPER MARGINAL PORTION OF SAID WEB PROJECTING ABOVE THE LEVELED UPPER SURFACE OF SAID SLAB BODY; SUBSEQUENTLY DEPRESSING SAID WEB INTO SAID CHANNEL, WHILE MAINTAINING CONTACT WITH BOTH SIDES OF THE LATTER, TO ALIGN ITS UPPER WEB EDGE WITH THE SURFACE OF THE SLAB BODY AND THEN ALLOWING THE CEMENTITIOUS MATERIAL OF THE SLAB TO HARDEN WITH THE CHANNEL AND WEB PERMANENTLY IMBEDDED THEREIN TO FROM A LINE OF WEAKNESS IN SAID SLAB ALONG THE PLANE OF SAID JOINT MEMBER. 